Conventionally, in the medical field, processing solution waste generated along with the wet process for image forming materials has caused problems regarding worakability, and in recent years, a decrease in the processing solution waste has been strongly demanded in terms of environmental protection and space savings. Thus, a technique for light heat photographic material for a technical photographic use is demanded in which exposure can be sufficiently carried out using a laser image setter or a laser imager, so that sharp and bright images with high resolving power can be achieved. Methods are well known such techniques which are described, for example, in U.S. Pat. Nos. 3,152,904 and 3,487,075 and D. Morgan, "Dry Silver Photographic Materials" (Handbook of Imaging Materials, Marcel Dekker, Inc. page 48, 1991), etc. These photosensitive materials are referred to as thermally developable photosensitive materials comprising a support having thereon an organic silver salt, a photosensitive silver halide, and a reducing agent. It is well known that an automatic processor for said thermally developable materials is advantageous in that it does not need relatively large scale processing tanks which are employed in most wet processes, but needs only a compact scale of the normal processing apparatus.